One of the trains for BART’s Oakland Airport Connector. (Isabel Angell/KQED)

BART’s Oakland Airport Connector has reached a new milestone this week: A train completed its first fully automated loop around the system from the Coliseum station to airport terminals.

The Oakland Airport Connector runs on a cable system — pretty similar to the San Francisco cable cars, but without drivers. The system has four cable loops and one train per cable. The trains automatically switch cables four times: once at each end, and halfway between the two stops.

That halfway point is called the wheelhouse, and inside are four giant wheels with spinning cables. The noise from those spinning cables is almost deafening.

Inside the Wheelhouse for BART’s Oakland Airport Connector, one of the giant wheels spins a cable to pull the train along. (Isabel Angell/KQED)

But outside, the trains are almost silent. You can barely hear cars as they approach.

“There’s no motors. The only hum you hear is from the air conditioner. Otherwise, it’s going to be dead silent.” said project manager Tom Dunscombe.

“It’s going to be like riding on a cloud. It’s amazing,” said Dean Hurst of Doppelmayr, an Austrian company that specializes in cable cars and other “ropeway” technologies.

“The suspension and the ride quality is excellent,” Hurst added.

The connector will replace AirBart, a tried-and-true shuttle bus system that’s been running since the 1970s.

“Between the Coliseum and the airport and back there’s nine intersections, and traffic can vary day to day depending on what events are happening,” Dunscombe said. “So, as was said, the reliability should be much greater. So we’re going to be delivering trains about every 4½ minutes to the Coliseum and to the airport.”

A look inside one of the trains for BART’s Oakland Airport Connector. The sandbags simulate a full load. (Isabel Angell/KQED)

The $484 million connector is scheduled to open in November. Each ride will cost $6 one way. A BART spokesman said senior, youth and disability discounts would apply to the fare. Airport workers will pay $2 per ride.